Screw-propeller.



No. 698,584. Patented Apr. 29

B. THALER.

SCREW PRUPELLEB.

(Application filed Jan. 20, 1902.)

(No Model.)

WITNESSES:

ATTORNEY UNITED STATES PATENT OFFICE.

ROBERT TI-IALER, OF WEST BAY CITY, MICHIGAN.

SCREW-PROPELLER.

SPECIFICATION forming part of Letters Patent No. 698,584, dated April29, 1902.

Application filed January 20, 1902. Serial No. 90,515. No modelJ ject ofthe Emperor of Germany, residing at West Bay City, in the county of Bayand State of Michigan, have invented certain new and useful Improvementsin Screw Propellers; and I do hereby declare the following to be a full,clear, and exact description of the inven-,

tion, such as will enable others skilled in the art to which itappertains to make and use the same.

This invention relates to an improvement in screw-propellers, the objectof the invention being to provide a simple and eflicient propellerhaving large area of blade-surface and large area of bearing-surfaceupon the projecting portion of the stern-post to prevent the shaft beingbent or broken when the blade strikes an obstruction.

Another object is to provide means for antomatically removing dirt andgrit from the rubbing-surfaces of the propeller and the projection onwhich it turns.

With this object in View the invention consists in certain novelfeatures of construction and combinations and arrangements of parts, ashereinafter set forth, and pointed out in the claim.

In the accompanying drawings, Figure l is a perspective View of thepropeller and shaft. Fig. 2 is a part-longitudinal section of thepropeller in place on the projecting bearing of the stern-post. Fig. 3is an enlarged section taken on the line as w of Fig. 1.

A represents the screw, the length of which is preferably somewhatgreater than the diameter. The blades are helical in form and inrevolving describe a cylinder of uniform diameter. The shaft 1 isrigidly secured, by means of the key 2, to the outer end of the hub andfits the bore of the hub tightly from its outer end to about its middle.The other end of the hub is provided with a conical recess 3, extendingaxially from the forward end of the screw and tapering to its smallerend 3 about midway the length of the screw. The inner surface of theconical recess is finished to form a smooth bearing-surface.

The stern-post of the vessel is fitted with a rearwardly-projecting boss4:, which carries at its outer end a conical bearing 4?, the outersurface of which exactly fits and forms a bearing for the inner surface3 of the revolving hub. The shaft 1 extends axially through theprojection 4 and the conical bearing 4:.

In order to remove dirt or other foreign substances from between therubbing-surfaces of the hub and the conical bearing 4:, I providethrough the shell of the .hub pairs of slits 5, separated byintermediate bars 5, through which the dirt can escape. In practice Iprefer to shape the intermediate bar 5 as shown in Fig. 3, having innerscraping edges 5 which mechanically remove the dirt from the surface ofthe bearing at and discharge it into the water through openings 5.

In practice I prefer to arrange a sufficient number of slits 5 aroundthe hub and to make them of such length that the paths of succeedingslits as they travel around the conical bearing will overlap, thusthoroughly cleaning every part of the rubbing-surface.

By constructing the hub of the screw-propeller as abovedescribed andmounting it upon the conical bearing 4, which is rigidly attached to thestern-post of the vessel, I produce a screw having great lateralrigidity and one which cannot be easily broken by striking snags orother obstacles.

What I claim as my invention, and desire to secure by Letters Patent, is

A propeller for vessels comprising in combination a series of helicalblades of greater length than the diameter of the propeller; a hubintegral with said blades; an axial hole through said hub, the outerportion of the length of said hole being adapted to fit thepropeller-shaft the remaining portion of said holebeing enlarged fromthe middle of the hub toward its forward end, to form a conical recess;openings through the conical shell of g

